Muffler



April 30, 1940.

B. ROBBINS MUFFLER Filed NOV. 17, 1938 Patented Apr. 30, 1940 UNiTED STATES rATENT @FFEQE.

MUFFLER Brewster G. Robbins, Utica, N. Y., assignor to 7 Claims.

The present invention relates to new and useful improvements in mufiiers, and more particularly to improvements in mufflers which are generally used for quieting the noise incident to the exhaust of gases from internal combustion engines.

The invention is concerned generally with the provision of a muflier of the type which includes a plurality of tubes disposed within the mufiler casing for causing the gases to pass therethrough in a circuitous path. The tubes extend through a plurality of baffle plates which divide the easing into a plurality of expansion chambers, and'these tubes are preforated or slotted to permit the gases to expand into the expansion chambers during their passage through the muflier casing. Muffiers of this type are generally classed as straight-through or tri-flow types. In the first type, there is generally provided a perforated central tube which extends substantially through the mufiier casing, and baffle plates are provided around the tube so as to provide a plurality of expansion chambers into which the gases can expand during their passage through the mufller. In the second type, a plurality of tubes are generally mounted within the muffler casing in parallel' relationship so that the exhaust gases pass through the muffler casing in a sinuous and reversely directed path. These tubes also pass through balile plates which afford expansion chambers into which the exhaust gases are successively expanded as they pass through the various tubes in the casing.

More particularly, the present invention is concerned with a muffler which includes a tri-flow portion or which includes both straightthrough and tri-flow portions. It often becomes necessary to change mufllers, and for this purpose, it is desirable to provide a muiiler which can be readily interchanged with already existing types of mufflers. When it is desired to substitute a tri-flow or combined tri-flow and straight-through muilier for some other type of mufiier construction, it is diflicult to provide an exact fitting within the muffler casing andwiththe exhaust pipe connections. The present invention is concerned with the provision of a muflier of this type which can be readily interchanged and which possesses certain novel characteristics and advantages.

An object of the present invention is to provide a muflier which is of relatively simple construction, which is inexpensive to manufacture, and which effects the desired quieting of the exhaust gases.

haust gases, and wherein the parallel tubes are 1 constructed so as to occupy a minimum. amount of space within the mufiler casing and, at the same time, permit the necessary freedom of movement of the gases therethrough.

A still further object of the invention is to pro 7 vide a muffler of the above type, wherein one of the paralleltubes is centrally located and adapted for connection to the exhaust pipe connection, and wherein the side parallel tubes are arcuately shaped in cross section so as to permit their disposition in the limited amount of space between the central tube and the mulfler casing.

The above and other objects of the invention will in part be obvious, and will be hereinafter more fully pointed out.

In the accompanying drawing,

Figure 1 is a side view, in section, showing the muffler assembly.

Figure 2 is an enlarged sectional View, taken along the line 2--2 of Figure 1.

Figure 3 is a similarly enlarged sectional view, taken along the line 3-3 of Figure 1.

Referring more in detail to the accompanying drawing, the mufiier assembly is illustrated as including an outer mufiler casing it, which is provided with end closures or heads ll, l2. These end closures ll, I2 are provided with outwardly extending flanges Ila, 12a, respectively, which are suitably secured, as by welding, to the inner surface of the muffler casing. The end closures are illustrated as being centrally apertured and provided with inwardly extending flanges I lb, [2b, respectively, around the apertures therethrough. An inlet pipe connection l3 leading from the internal combustion engine (not shown) has the inner end l3a thereof slightly offset and disposed within the flange Hb on the closure H. An exhaust pipe connection I4 is provided with a similar offset end portion Ma which is disposed within the flange l2b on the end closure [2.

In the illustrated embodiment of the invention, a centrally disposed tube I5 has one end thereof suitably secured, as by Welding, within the portion I30: of the inlet pipe connection 13. This tube 15' is perforated in any suitable manner, as

by the provision of groups of slots l6, and extends only partially through the mufller casing III. A pair of spaced baflle plates l1, l8 are provided with outer flanges ||a, |8a, respectively, which are welded or otherwise secured to the inner surface of the mufller casing. These baflie plates [1, I8 are also provided with inner flanges I'Ib, l8b, respectively, which are secured around the tube IS. The bafiie plates l1, l8 are also provided with an annular ring of apertures l'lc, |8c, respectively. The end closure II and the bafile plate I! define an expansion chambenA which communicates with the tube l5 through groups of slots l6 therein. Similarly, the bafiie plates I1 and I8 define an expansion chamber B which is also in communication with the tube IS.

A centrally disposed tube l9 has one end |9a thereof suitably secured within the end portion |4a of the exhaust pipe connection I 4 and extends through a relatively large portion of the mufiler casing. At opposite sides of the central tube Hi there are provided tubes 20, 2| which are illustrated as being parallel to the central tube I9 and arcuately shaped in cross section, as particularly shown in Figure 3. The arcuate shaping of the tubes 2|], 2|, is taken substantially about the central axis of the tube l9. Thus, the tubes 20, 2| afford a relatively large interior conduit portion, but occupy a minimum amount of space so that they can be conveniently positioned between the mufiler casing l0 and the center tube IS. The arcuate tubes 20, 2| are entirely separate units and independent of each other and of the central tube I9. The inner wall portions of the tubes 20, 2| are spaced outwardly from, the central tube l9 and are parallel thereto, while the outer wall portions of the tubes 20, 2| are spaced inwardly from the adjacent inner surface of the muffler casing and are parallel thereto. Thus, the tubes I9, 20 and 2| afford separate conduits for the passage of gases.

Baffle plates 22, 23, 24, 25 are each provided with flanges by which they are suitably secured in spaced relationship to the interior surface of the muffler casing. These bafiie plates are also apertured and properly shaped so that the tubes H1, 20, 2| can extend therethrough. Thus, there is provided an expansion chamber C between the baffle plates 22, 23, an expansion chamber D between the bafile plates 23, 24, and an expansion chamber E between the bafile plates 24, 25. The tube 20 is provided with groups of perforations in the form of slots 26 which afford communication between this tube and the expansion chamber C. The central tube I9 is provided with groups of slots 30 in the center portion thereof and these slots afford communication between this tube and the expansion chamber D.

The inner end 2011 of the tube 20 is extended and a bafile plate 3| is provided with flanges 3|b which are secured around the extended end of the tube 2|]. The baffle plate 3| is also provided with outer flanges 3 la which are suitably secured to the inner surface of the casing l0. There is thus provided an intermediate expansion chamber F between the baffle plate I8 and the baffle plate 3|. The baffle plate 3| prevents direct communication between the tubes l9, 2| and the chamber F, although the tube 20 is in communication with the chamber F. A chamber G is provided between the end closure l2 and the baffle plate 25, and this chamber provides communication between the tubes 20, 2|. The end |9a of the central tube l9 extends through this chamber and is not in direct communication therewith.

Gases entering the muffler through the pipe connection I3 are directed into the tube IS. A portion of these gases is expanded into the chambers A and B through the slots |6 during their passage through the tube. A portion of the gases expanded into the chambers A and B may also be directed through the openings I10, I into the chamber F. The gases issuing from the inner end of the tube l5 are further expanded in the chamber F and then pass through the tube 20. During the passage of the gases through the tube 20, a portion thereof gains access to the expansion chamber 0 and then passes through the chamber G into the return tube 2 During the passage of the gases through the tube 2|, 2, portion thereof is expanded into the expansion chamber E and then passes into the inner end of the central tube IS. The gases passing through the central tube l9 toward the exhaust pipe connection M are further expanded through the perforations 30 into the expansion chamber D.

From the foregoing description, it will be seen that the illustrated form of muffler includes a relatively short straight-through portion and a relatively long tri-flow portion. It is to be understood, however, that the tri-ilow portion of the muffler may constitute the entire inner assembly. The present construction provides a muffler wherein a cylindrical tube within the muffler casing is adapted to be directly connected to the exhaust pipe connection of the muffler. The side tubes are shaped so as to occupy a minimum amount of space between the cylindrical tube and the muffler casing, thus providing an inner mufiler assembly which may be substituted and placed within a relatively small mufiler casing. The cylindrical tube may be positioned with respect to the side tubes so that it can be directly connected to the exhaust pipe connection. In the illustrated embodiment of the invention, the cylindrical tube is illustrated as being centrally disposed for attachment to a centrally disposed exhaust pipe connection. In this form of the invention, the arcuate-shaped side tubes are disposed at diametrically opposed points with respect to the center tube, and these side tubes are shaped about the central axis of the muffler casing so as to occupy a minimum amount of space between the center tube and the inner surface of the muffler casing. However, the side tubes, while arcuately shaped in cross section, are elongated so as to provide the desired internal area permitting the free flow of gases therethrough.

The illustrated form of muffler is one which may be connected to centrally disposed inlet and exhaust connections so that the gases are caused to pass in a sinuous and reversely directed path through a portion of the mufiier. The baffle plate 3| prevents direct communication between the tubes I9, 2| and the inlet portion of the muilier, but permits the tube 20 to communicate therewith. The end closure |2 prevents direct communication between the tubes 20, 2| and the exhaust pipe connection, but permits the central tube |9a to be directly attached thereto.

While one form of the invention has been shown in the drawing, it is to be clearly understood that various changes in the details of construction and arrangement of parts may be made without departing from the scope of the invention as set forth in the appended claims.

I claim:

1. A muffler comprising a casing, a plurality of spaced baffle plates secured to the inner surface of said casing for providing expansion chambers, and a plurality of separate parallel tubes entirely independent of one another extending through said baffle plates for providing separate passages for the gases and being perforated to permit the passage or gases into said expansion chambers, one of said tubes being directly connected to an exhaust pipe connection, and the other of said tubes being arcuately shaped in cross section about the center axis of said first tube whereby the said tubes occupy a minimum amount of space within the casing.

2. A muffler comprising a cylindrical casing, a plurality of spaced baffle plates secured to the inner surface of said casing for providing expansion chambers, a centrally disposed cylindrical tube disposed within said casing and extending through said baiile plates, said tube being directly connected to an exhaust pipe connection, and a pair of separate side tubes entirely independent of each other and of said cylindrical tube and arcuately shaped in cross section about the central axis of said casing and disposed at diametrically opposed points with respect to said central tube, said tubes being perforated to permit passage of the gases into said expansion chambers and said side tubes havingthe inner Wall portions thereof spaced outwardly from and parallel to the adjacent Wall of said cylindrical tube and having the outer wall portions thereof spaced inwardly from and parallel to the inner surface of said casing.

3. A mufiier comprising a casing, a plurality of spaced banie plates disposed at one end of said casing for providing expansion chambers, a centrally disposed inlet tube extending through said bafiie plates and being perforated to permit the passage of gases into said expansion chambers, a plurality of spaced ,baiiie plates secured to the inner surface of the opposite end of the casing and providing additional expansion chambers, and a plurality of separate parallel. tubes entirely independent of one another extending through the latter group of bafile plates and being perforated to permit the passage of gases into the latter group of expansion chambers.

l. A muffler comprising a casing, a plurality of spaced baffle plates disposed at one end of said casing for providing expansion chambers, a centrally disposed inlet tube extending through said baflie plates and being perforated to permit the passage of gases into said expansion chambers, a plurality of spaced baffle plates secured to the inner surface of the opposite end of the casing and providing additional expansion chambers, and a plurality of separate parallel tubes entirely independent of one another extending through the latter group of bailie plates and being perforated to permit the passage of gases into the latter group of expansion chambers, one of said parallel tubes being centrally disposed within said casing and directly connected to an exhaust pipe connection and the other of said parallel tubes being disposed between said centrally disposed tube and said casing and being arcuately shaped in cross section about the central axis of the casing whereby the said parallel tubes occupy a minimum amount of space within the casing.

5. A muffler comprising a casing, a plurality of baffle plates secured to the inner surface of said casing for providing expansion chambers, a plurality of separate parallel tubes entirely independent of one another extending through said bafile plates and being perforated to permit the passage of gases to said expansion chambers, one of said tubes being directly connected to an exhaust pipe connection and the other of said tubes being disposed between the tube connected to the exhaust pipe and said casing and arcuately shaped in cross section, and a partition wall disposed within the casing and through which one of said arcuate-shaped tubes extends for communication with the inlet end of the muffler, said partition wall preventing direct communication between the other of said tubes and the inlet end of the muffler.

6. A mufiier comprising a casing, a plurality of baiiie plates secured to the inner surface of said casing for providing expansion chambers, a centrally disposed cylindrical tube extending through said baffle plates and directly connected to an exhaust pipe, connection, said tube being perforated intermediate the ends thereof for affording communication with one of said expansion chambers, and a pair of separate tubes disposed between said cylindrical tube and said casing and at diametrically opposed points with respect to said central tube and extending through said baffle plates, said parallel tubes being arcuately shaped in cross section about the center axis of said central tube with the inner wall portions thereof spaced outwardly from and parallel to the wall of said cylindrical tube and with the outer wall portions thereof spaced inwardly from and parallel to the inner surface of said casing and being perforated to afford communication with each of said expansion chambers.

7. A muffler comprising a casing, a plurality of baffle plates secured to the inner surface of said casing for providing expansion chambers, a centrally disposed cylindrical tube extending through said baffle plates and directly connected to an exhaust pipe connection, said tube being perforated intermediate the ends thereof for affording communication with one of said expansion chambers, and a pair of separate parallel tubes disposed between said cylindrical tube and said casing and at diametrically opposed points with respect to said central tube and extending through said baffle plates, said parallel tubes being arcuately shaped in cross section about the center axis of said central tube and being perforated at opposite ends whereby each will afford communication with another of said expansion chambers.

BREWSTER G. ROBBINS. 

